The present invention relates to an image sensor, an image signal processing method, an image signal processing system, and an image sensing apparatus.
In an image signal processing circuit which deals with color signals, variety of image signal processes are usually performed. Generally, in the image signal processes, signals are processed by pixel blocks of a predetermined size.
There are various kinds of image signal processes which are performed by pixel blocks of the predetermined size, and summation of differences between adjoining pixels, summation of weighted signals of pixels in the pixel block, and filtering, for instance, are included in such image signal processes.
A conventional image sensing apparatus which performs filtering operation by pixel blocks is explained with reference to FIG. 33.
FIG. 33 is a block diagram illustrating a configuration of the conventional image sensing apparatus. In FIG. 33, reference numeral 901 denotes a charge-coupled device (CCD) image sensor; 902, an analog-digital (A/D) converter; 903, memory; 904, a spatial filter; 905, a digital-analog (D/A) converter.
In the CCD image sensor 901, a photoelectric signal obtained in each photoelectric conversion element of the image sensor 901 is first transmitted in the vertical direction, then in the horizontal direction. More specifically, after all the photoelectric signals in a given row are transferred in the vertical direction and arrive at a horizontal transfer unit, the photoelectric signals of the given row are transferred in the horizontal direction by the horizontal transfer unit and sequentially outputted from an output terminal. The above operation is performed for every row. Therefore, photoelectric signals of pixels of the image sensor 901 are sequentially outputted in the scanning order as shown by solid arrows in the image sensor 901 in FIG. 33.
The photoelectric signals outputted from the image sensor 901 are converted into digital signals by the A/D converter 902, then stored in the memory 903. Thereafter, digital signals corresponding to, e.g., 3xc3x973 pixel area (i.e., block) are outputted from the memory 903 and enter the spatial filter 904. The spatial filter 904 performs filtering processes using, e.g., a low-pass filter and a band-pass filter on the inputted digital signals, then outputs the filtered signals. The D/A converter 905 performs digital-analog conversion on the filtered signals and outputs analog image signals.
Thus, image signal processes, such as the filtering operation as described above, are conventionally performed on photoelectric signals (pixel signals) which are serially outputted from an image sensor to a signal processing circuit. Therefore, in order to process the signals by pixel blocks, the signal processing circuit has to wait until all the pixel signals are outputted from the image sensor.
Further, memory is needed for processing pixel signals by pixel blocks, and the memory required in this operation should have a large capacity.
More specifically, in the image sensing apparatus performing the filtering operation as described above, for instance, it is necessary to store pixel signals in the memory 903 for providing the pixel signals by pixel blocks to the spatial filter 904. In a case where the spatial filter 904 processes signals by the 3xc3x973 pixel block, the memory 904 needs to have a capacity to store signals of two rows. In this case, an image signal outputted from the spatial filter 904 is lagging by one row behind a pixel signal outputted from the image sensor 901. In addition, there is a delay since photoelectric signals are obtained in the respective pixels until the photoelectric signals are actually outputted from the image sensor 901 after being transferred within the image sensor 901.
Further, in the aforesaid conventional image sensing apparatus, it is necessary to have an IC chip, including the A/D converter 902, the memory 903, the spatial filter 904, and the D/A converter 905 separately an IC chip of the image sensor 901.
Therefore, neither good cost performance nor the high-speed image signal processing can be expected when a variety of image signal processes are to be performed in the conventional signal processing circuit.
The present invention has been made in consideration of the above situation, and has as its object to provide an image sensing device, an image sensing apparatus, and an image signal reading and processing method capable of simplifying a configuration of a signal processing circuit which calculates sum of products or performs spatial filtering processing on image signals by blocks, thereby improving processing speed in the signal processing circuit.
According to the present invention, the foregoing object is attained by providing an image sensing device comprising: a sensor unit having a plurality of pixels; control means for controlling to read signals from the sensor unit by pixel blocks of a predetermined size; and signal processing means for calculating sum information of the signals, read from the sensor unit, by pixel blocks of the predetermined size.
Further, the foregoing object is also attained by providing an image sensing apparatus comprising: a sensor unit having a plurality of pixels; control means for controlling to read signals from the sensor unit by pixel blocks of a predetermined size; signal processing means for calculating sum information of the signals, read from the sensor unit, by pixel blocks of the predetermined size; and compression means for compressing the sum information calculated by the signal processing means.
Furthermore, the foregoing object is also attained by providing an image signal reading and processing method comprising: a reading step of reading signals of a plurality of pixels by pixel blocks of a predetermined size; and a signal processing step of calculating sum information of the signals read by pixel blocks of the predetermined size in the reading step.
Further, the foregoing object is also attained by providing an image sensing device comprising: a sensor unit having a plurality of pixels; control means for controlling to read signals from the sensor unit by pixel blocks of a predetermined size; and a spatial filter for performing spatial filtering on the signals, read from the sensor unit, by pixel blocks of the predetermined size.
Further, the foregoing object is also attained by providing an image signal reading and processing method comprising: a reading step of reading signals of a plurality of pixels by pixel blocks of a predetermined size; and a spatial filtering step of performing spatial filtering on the signals, read in the reading step, by pixel blocks of the predetermined size.
Further, it is another object of the present invention to provide an image sensing device and an image signal reading method capable of reading image signals in the optimum condition for being processed with signal processes by blocks.
According to the present invention, the foregoing object is attained by providing an image sensing device comprising: a sensor unit having a plurality of pixels; vertical selection means for selecting pixels of the sensor unit by a row; horizontal selection means for selecting pixels of the sensor unit by a column; and output means for outputting signals from pixels which are selected by both of the vertical selection means and the horizontal selection means.
Further, the foregoing object is also attained by providing a reading method for reading signals from a sensor unit having a plurality of pixels, the method comprising: a vertical selection step of selecting pixels of the sensor unit by a row; a horizontal selection step of selecting pixels of the sensor unit by a column; and an output step of outputting signals from pixels which are selected in both of the vertical selection step and the horizontal selection step.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.